Chapter 4 Results

4.1 Global spatial data for cases & deaths

Here we present the global map of cumulative cases per 100000 population, deaths per 100000 population, and persons vaccinated 1+ doses per 100 population. The map is interactive. Put the mouse over a particular area, and the detailed data will appear. The maps can be zoomed in by clicking the buttons on the left and be dragged by holding the left button of the mouse. The data is updated on 2022/12/05.

We can see from the graphs that European countries show high infection rates, followed by the Americas. The reported infection rate in Asia and Africa is relatively late. The bordering countries show similar infection rates, while the countries with strict covid-19 policies show lower rates compared to surrounding countries, for instance, China. It has been noted on the WHO website that the case and death data for the Region of Africa are incomplete. Therefore the actual infection rates in Africa may be higher than reported.

Countries with high infection rates are more likely to report more deaths. For the vaccination data, we can see that countries in Europe and in the Americas tend to show higher vaccination rates, which are the richer countries with more medical resources.

We find from the data that the death rates are relatively high in the US compared to countries with similar or even higher infection rates in Europe. For example, the infection rate in the US is 29491/100000, and the death rate is 324/100000, while the figures for France are 566638/100000 and 238/100000. We first infer that it may be caused by the difference in calculating death cases. In the US, if COVID-19 appears among the causes and contributors, CDC guidance counts that as a COVID-19-related death. Some countries in Europe record solely deaths of those who have been tested and that occurred in the hospital. But for countries like France and German, their case numbers include those who died “of” COVID-19 and those who died “with” the disease, both in hospitals and care houses. The United Kingdom has been reporting all deaths after a positive test within 60 days as a coronavirus death. So the different counting methods in Europe may not be the main cause of the lower rates of deaths here. The reasons behind these differences may be complicated. From the data we have now, the US shows similar vaccination rates, and the differences may be caused by medical resources, various types of social distance measures, and time affected by Covid-19.

4.2 Time series analysis for Covid-19 cases and deaths worldwide

Covid-19 started at the beginning of 2020, and spread quickly accross the world. To analyze the overall spread pattern of the pademic, we analyze the global cases and deaths data as a time series. By plotting the time series by day, we observed a strong cyclic pattern, making the data very noisy. This is because of the delay of data update during weekends of the original dataset. To remove the cyclic pattern, it’s better to use the weekly time series.

From the two weekly time series, we observed the following patterns.

The first spike of reported deaths appeared in April 2020, with no spike in reported cases at the same time. This refer to the early spread in China. The low cases and high deaths also indicate the high fatality rate of the virus at the beginning.
In January 2021, both the reported cases and reported deaths experience a relatively strong spike. During this time, the has pandemic spreaded worldwide, and contries in Europe and America are experiencing a high infection rate of Covid-19.
The reported cases and deaths began decreasing slowly with vaccination being available since December 2020.
The most outstanding spike of reported cases appeared in January 2022, with over 20 million weekly new cases around the world. This was over four times of that in January 2021. This was exactly the time when Omicron variant spread drastically accross the world. However, the report deaths did not increase that much at the mean time, from which we could conclude that Omicron spreads more easily than earlier variants, but causes less severe illness and death in general.

4.3 Time series analysis for Covid-19 cases & deaths in the U.S.

The United States is the country with the highest number of confirmed cases and deaths. The count of known new cases is the closest thing we have to a real-time gauge of the coronavirus’s reach. The introduction and widespread availability of COVID-19 vaccines has led to changing patterns of COVID-19 morbidity and mortality over the course of the pandemic.

The weekly time series is a better way to view trends in new cases and deaths. It also can serve as a warning: if cases suddenly rise, hospitalizations and deaths almost certainly will follow.

As we can see from the chart, we observed the following patterns:

A rise in deaths usually follows a rise in new cases by about a month. For example, after the delta variant caused a surge of new cases beginning in July 2021, the death toll began to climb in August.
COVID-19–related deaths substantially decreased in the United States in March 2022. During April - early November 2022, this initial decline was largely sustained and the overall number of COVID-19 related deaths remained relatively stable.
During January 2022, new cases sharply rose again amidst the spread of the Omicron variant, resulting in the highest case rates recorded since the start of the pandemic. By February 2022, new cases had fallen sharply, and disparities once again narrowed.

4.4 Understanding overall vaccination data in the U.S.

In this section, we focus on the U.S. COVID-19 vaccination data. By analyzing and visualizing the data, we try to answer the following questions - what is the overall level of US vaccination comparing to global data? How many Americans have been fully vaccinated while how many of them haven’t taken any vaccination? Which state has the highest vaccination rate?

We first draw a boxplot of the fully vaccinated rate of different countries across the world. The median of global fully vaccinated rate is 61.165, while the US fully vaccinated rate is 67.989, which is between the median and third quantile of the global data.

To understand the different vaccination state of the US population, we produced a stacked bar chart. We observed that 68% of the US population has been fully vaccinated, among which 33.7% of the population has taken the booster. However, there are still 20.3% of the population who have not taken any vaccine.

A deeper insight of the vaccination in the US would be dividing the total population by age groups. From the grouped bar chart below, both the vaccinated and fully vaccinated rate grow with the age groups. People aged over 65 have the highest fully vaccinated rate of 88.6% and vaccinated rate of 95%. This is reasonable because the old people are more prone to be infected by the virus, so they are more likely to take the complete series of vaccines. Children less than 12 years are too young so their parents may worry about the side effects of the vaccine, so they have a lowest fully vaccinated rate of 16.7% and a vaccinated rate of 25.6%.

4.5 Exploring vaccination progress by U.S. state

To explore U.S. vaccination efforts, we draw the boxplot of the fully vaccinated rate by state. The median of U.S. fully vaccinated rate is 66.3%, while the U.S. average fully vaccinated rate is 68.9%.

To compare states’ vaccination progress, we produced the Cleveland dot plot below. We can see that these are the states, territories with the highest fully vaccination rates: Rhode Island, Puerto Rico, Vermont, D.C., and Massachusetts. Over half of the states’ fully vaccination rates are below U.S. average rate.

4.6 How effective are vaccines at reducing the infection rate?

The blue dash-dotted line is the cumulative daily cases over time (right y-axis). The red dash-dotted line is the cumulative vaccination coverage of fully vaccinated individuals in the population (right y-axis). The chart shows a timeline of COVID-19 developments during the pandemic, including important events and vaccination timeline.

We can see that the new infections slow down after the vaccine rollout in December 2020. During January 2022, the Omicron variants have been particularly immune-evasive and drove the largest surge in COVID-19 cases to date. COVID-19 monovalent vaccines available at the time were not as efficacious against the variant as bivalent boosters introduced later, but the wave would have been more devastating in the absence of vaccination.

A limitation of our study is that we modeled only viral dynamics within the U.S. However, vaccines developed by the U.S. were also deployed around the world, changing the trajectory of the pandemic on a global scale. Without them, more variants could have emerged or there could have been greater importation of COVID-19 cases.